CST_BEI_Weighting {CSTools}

Weighting SFSs of a CSTools object.

Description

Function to apply weights to a 's2dv_cube' object. It could return a weighted ensemble mean (deterministic output) or the terciles probabilities (probabilistic output) for Seasonal Forecast Systems (SFSs).

Usage

CST_BEI_Weighting(
  var_exp,
  aweights,
  terciles = NULL,
  type = "ensembleMean",
  time_dim_name = "time",
  memb_dim = "member"
)

Arguments

var_exp

An object of the class 's2dv_cube' containing the variable (e.g. precipitation, temperature, NAO index) array. The var_exp object is expected to have an element named $data with at least a temporal dimension and a dimension named 'member'.

aweights

Normalized weights array with at least dimensions (time, member), when 'time' is the temporal dimension as default. When 'aweights' parameter has any other dimensions (as e.g. 'lat') and 'var_exp' parameter has also the same dimension, they must be equals.

terciles

A numeric array with at least one dimension 'tercil' equal to 2, the first element is the lower tercil for a hindcast period, and the second element is the upper tercile. By default is NULL, the terciles are computed from var_exp data.

type

A character string indicating the type of output. If 'type' = 'probs', the function returns, in the element data from 'var_exp' parameter, an array with at least two or four dimensions depending if the variable is spatially aggregated variable (as e.g. NAO index), dimension (time, tercil) or it is spatial variable (as e.g. precipitation or temperature), dimension (time, tercile, lat, lon), containing the terciles probabilities computing with weighted members. The first tercil is the lower tercile, the second is the normal tercile and the third is the upper tercile. If 'type' = 'ensembleMean', the function returns, in the element data from 'var_exp' parameter, an array with at least one or three dimensions depending if the variable is a spatially aggregated variable (as e.g. NAO index)(time) or it is spatial variable (as e.g. precipitation or temperature) (time, lat, lon), containing the ensemble means computing with weighted members.

time_dim_name

A character string indicating the name of the temporal dimension, by default 'time'.

memb_dim

A character string indicating the name of the member dimension, by default 'member'.

Value

CST_BEI_Weighting() returns a CSTools object (i.e., of the class 's2dv_cube'). This object has at least an element named $data with at least a temporal dimension (and dimension 'tercil' when the output are tercile probabilities), containing the ensemble means computing with weighted members or probabilities of terciles.

Author(s)

Eroteida Sanchez-Garcia - AEMET, [e-mail]

References

Regionally improved seasonal forecast of precipitation through Best estimation of winter NAO, Sanchez-Garcia, E. et al., Adv. Sci. Res., 16, 165174, 2019, doi: 10.5194/asr-16-165-2019

Examples

var_exp <- 1 : (2 * 4 * 3 * 2)
dim(var_exp) <- c(time = 2, member = 4, lat = 3, lon = 2)
aweights <- c(0.2, 0.1, 0.3, 0.4, 0.1, 0.2, 0.4, 0.3, 0.1, 0.2, 0.4, 0.4, 0.1, 
             0.2, 0.4, 0.2)
dim(aweights) <- c(time = 2, member = 4, dataset = 2)
var_exp <- list(data = var_exp)
class(var_exp) <- 's2dv_cube'
res_CST <- CST_BEI_Weighting(var_exp, aweights)